I planted some bags of water-loving Irises in Middle Garden some years ago. But I placed them too close to the Gunnera, and they became completely shaded out by the huge Gunnera leaves.
Yellow Japanese Irises
The answer was easy - I just dug them up and replanted them slightly lower down the water race, in the sun. Very pretty! I've always called these Japanese Irises. Their main colour is this brilliant yellow, with just a few whites and a pale blue. Next flowering I'll try and get more photographs.